Prosthetic urethral valves of the prior art for incontinent patients involve numerous disadvantages. Most urethral valves of the prior art utilize an inflatable cuff around the outside of the urethra, or a catheter that extends beyond the distal end of the urethra. The former type of urethral valve requires surgery for installation, and the latter type is noncosmetic and invites infection. Also, a number of the previously proposed urethral valve devices must be operated externally and therefore are dependent on manual intervention.
Exemplary prior art devices which suffer from the above-discussed disadvantages are disclosed in U.S. Pat. Nos. 2,638,093 to Kulick; 3,372,695 to Beliveau; 3,903,894 to Rosen et al; 4,167,952 to Reinicke; 4,209,010 to Ward et al; 4,222,377 to Burton; 4,256,903 to Helms et al; and 4,386,601 to Trick.
A more recent intra-urethral prosthetic sphincter valve is disclosed in U.S. Pat. No. 4,553,533 to the present inventor. This device solves many of the disadvantages associated with prior devices, but utilizes a linear spring characteristic which requires a patient to exert increased pressures to maintain the opening of the valve element.
There remains a definite need for a non-surgically installed prosthetic urethral valve which has functional sensitivity to the natural physiological sustained internal bladder pressure produced voluntarily by the patient.